"It's not only about Messi, but of course it's about him as well," Klopp said. "Can we concentrate on Messi? We should in a lot of moments. But, if we only concentrate on him, there are 10 other world-class players who can decide the game as well."
Barcelona go into the first leg of the semi-final four days after securing the La Liga title for the eighth time in 11 years. Messi came off the bench to score the only goal of the game against Levante.
However the 31-year-old Argentine has targeted the Champions League trophy as a priority after Real Madrid's hat trick of titles.
"Now that we've been to the final and we are here again in the semi-final, all I can say is we want to go to the final as well," said Klopp.
The German has menace at his disposal in the shape of Mohamed Salah, Sadio Mané and Roberto Firmino. The troika have 68 goals this season between them.
"We need to stop them running at our defence," said Barcelona midfielder Ivan Rakitic. "We are going into the game to score, but we mustn't lose our heads."
Klopp added: "A draw would not be the worst result in the world. Not that we would go for that, but it would be okay.
"It would mean a lot to win, but it will be difficult. So many teams come to the Camp Nou with an idea to do this or that, and they get a big knock."
Having already secured La Liga, Barcelona have the chance of a domestic double with a final in the Copa del Rey against Valencia on 25 May.
However, the target for Barcelona over the next two fixtures against Liverpool is a place in the Champions League showdown seven days after the Copa del Rey final.
"We know in these ties that one good game is not enough," said Barcelona coach Ernesto Valverde. "You need to play two great games. If you switch off for five minutes against Liverpool, they can finish you off."